Semiconductor memory device and manufacturing method thereof

ABSTRACT

A semiconductor memory device has a plurality of core chips and an interface chip, whose specification can be easily changed, while suppressing the degradation of its reliability. The device has an interposer chip. First internal electrodes connected to core chips are formed on the first surface of the interposer chip. Second internal electrodes connected to an interface chip and third internal electrodes connected to external electrodes are formed on the second surface of the interposer chip. The interface chip can be mounted on the second surface of the interposer chip whenever desired. Therefore, the memory device can have any specification desirable to a customer, only if an appropriate interface chip is mounted on the interposer chip, as is demanded by the customer. Thus, the core chips do not need to be stocked in great quantities in the form of bare chips.

TECHNICAL FIELD

The present invention relates to a semiconductor memory device and amanufacturing method thereof. More particularly, the invention relatesto a semiconductor memory device in which a core unit having memorycells is integrated independently of an interface unit, and to a methodof manufacturing a semiconductor memory device of this type.

BACKGROUND OF THE INVENTION

In recent years, the storage capacity of semiconductor memory devices,represented by a DRAM (Dynamic Random Access Memory), has increased. Itis increasingly demanded that these devices can operate at higherspeeds. The increase in storage capacity has been achieved by makingmemory cells smaller and by increasing the chip size. However, theminiaturization of memory cells is physically limited, and the increasein chip size leads to a reduction of yield and impairs an increase ofoperating speed.

To solve these problems fundamentally, there has been proposed a methodsuch that a core unit having memory cells and an interface unit havingperipheral circuits to the memory cells are provided as chips that areindependent of each other, and a plurality of core chips can beallocated to one interface chip (see Japanese Patent ApplicationLaid-open No. 2004-327474). This can greatly decrease the size of eachchip. In view of this, the method is expected to increase the storagecapacity of semiconductor memory devices even more, while preservinghigh yield of the semiconductor memory devices.

Assume that the core unit and the interface unit are separate chips. Thecore chip and the interface chip can be fabricated in a memory processand a logic process, respectively. Generally, transistors made in thelogic process can operate at higher speed than the transistors made inthe memory process. Hence, if the interface chip is manufactured in thelogic process, it can operate faster than the conventional interfacechips. As a result, the interface chip enables the semiconductor memorydevice incorporating it to operate at high speed. Furthermore, theoperating voltage of the interface chip can be lowered by about 1V,which helps to reduce the power consumption in the semiconductor memorydevice.

FIG. 18 is a schematic sectional view showing the structure of aconventional semiconductor memory device.

As shown in FIG. 18, the conventional semiconductor memory deviceincludes an interposer substrate 10, an interface chip 20, and aplurality of core chips 31 to 34 (four core chips, for example). Theinterface chip 20 is provided on one surface 10 a of the interposersubstrate 10. The core chips 31 to 34 are mounted on the interface chip20 one on another. The device gives and receives signals to and from anexternal device through external terminals 11. The exchange of signalsbetween the interface chip 20 and the core chips 31 to 34 is performedthrough internal terminals 40 provided on the interface chip 20 and thecore chips 31 to 34, and through electrodes 41 penetrating the providedon the interface chip 20 and the core chips 31 to 34. In thissemiconductor memory device, the signals received through the internalterminals have greater widths than the signals received through theexternal terminals 11. The interface chip 20 changes the widths of thesignals.

More specifically, the signals (addresses, commands, write data or thelike) output from an external circuit via the external terminals 11 aresupplied to the interface chip 20, expanded by the interface chip 20 interms of signal width, and supplied to the core chips 31 to 34.Conversely, the signals (read signals or the like) output from the corechips 31 to 34 are supplied to the interface chip 20, compressed by theinterface chip 20 in terms of signal width, and output via the externalterminals 11 provided on the interposer substrate 10. Thus, the devicecan greatly increase the band width of signals to supply and receive toand from logic circuits such as CPUs that operate at high speed,although unable to perform large-scale parallel processing incorporation with the memory cores such as DRAMs that operate at lowspeed.

Semiconductor memory devices, such as DRAMs, are available in variousspecifications, even though they are of the same type. They differ inthe width of input and output data (e.g., the difference between ×8model and ×16 model), in clock frequency (e.g., the difference between200 MHz model and 266 MHz model). This difference in the specificationscomes mainly from the circuit configuration of the interface chip 20.The conventional semiconductor memory devices cannot changed inspecification once the layers have been laid one on another, because theinterface chip 20 and the core chips 31 to 34 are mounted, at a time, onthe interposer substrate 10. Inevitably, they cannot be flexiblymanufactured on demand to meet the customers' needs.

To solve this problem, the interface chip 20 and the core chips 31 to 34can be stocked in great quantities, not laid one on another, until thespecification of the semiconductor memory device to manufacture isformulated. However, this method is disadvantageous in that bare chips,i.e., chips not encapsulated yet, possibly remain long exposed toexternal conditions. In particular, core chips probably become defectiveif exposed to the external conditions for a long time. If they arestocked in large quantities and not encapsulated, they may degrade thereliability of the semiconductor memory devices, i.e., final productsincorporating them.

SUMMARY OF THE INVENTION

The present invention has been achieved to solve the problem describedabove. Therefore, an object of the present invention is to provide asemiconductor memory device has a plurality of core chips and aninterface chip, whose degradation of its reliability.

The semiconductor device according to the present invention includes: aninterposer chip that has a plurality of first internal electrodes formedon a first surface, a plurality of second internal electrodes formed ona second surface opposite to the first surface, a plurality of thirdinternal electrodes formed on the second surface and arranged in apitch, which is larger than a pitch of the second internal electrodes;and a plurality of core chips that are mounted on the first surface ofthe interposer chip and are connected to the first internal electrodes,wherein the interposer chip includes a semiconductor substrate, are-wiring layer formed on at least one surface of the semiconductorsubstrate, a plurality of first through electrodes formed in thesemiconductor substrate and connecting a part of the first internalelectrodes to a part of the second internal electrodes, and a pluralityof second through electrodes formed in the semiconductor substrate andconnecting a remaining part of the first internal electrodes to a partof the third internal electrodes, and a pitch of the first throughelectrodes is substantially equal at least to the pitch of the firstinternal electrodes or to the pitch of the second internal electrodes.

In the present invention, the core chips are mounted on the secondsurface of the interposer chip whenever desired. Therefore, productionsof various specifications can be easily provided. More specifically,appropriate interface chips that the customers have select are mountedon the semiconductor memory devices, thus easily providing semiconductormemory devices. The core chips do not need to be stocked in the form ofbare chips, in great quantities. It is therefore possible to flexiblymanufacture semiconductor memory devices on demand to meet thecustomers' needs, while suppressing the degradation of reliability ofthe products.

Since a pitch of the first through electrodes is substantially equal toa pitch of the first internal electrodes or a pitch of the secondinternal electrodes, or both, wires do not need to be guided so much onthe re-wiring layer. The through electrodes are arranged at such anarrow pitch, because the main component of the interposer chip is asemiconductor substrate. The through electrodes cannot be arranged atsuch a narrow pitch if the main component of the interposer chip is anordinary substrate such as a resin substrate or a ceramic substrate.

Before the interface chip is mounted on it, the semiconductor memorydevice according to the present invention cannot be connected toexternal electrodes. However, such an unfinished product is also called“semiconductor memory device” herein.

Preferably, the pitch of the first through electrodes is substantiallyequal to the pitch of the first internal electrodes and the pitch of thesecond internal electrodes. If so, the wires can be less guided on there-wiring layer.

Meanwhile, a method of manufacturing a semiconductor memory deviceaccording to the present invention includes a step of mounting aninterface chip on the second surface of the interposer chip incorporatedin the semiconductor memory device of the type described above, so thatthe interface chip is connected to the second internal electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of this inventionwill become more apparent by reference to the following detaileddescription of the invention taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a sectional view of a semiconductor memory device 100according to a first embodiment of the present invention;

FIG. 2 is a schematic plan view of an interposer chip 110, as viewedfrom a mounting surface;

FIG. 3 is an enlarged sectional view of a section X of shown in FIG. 1;

FIG. 4 is a schematic sectional view of the configuration of thesemiconductor memory device 100, on which an interface chip 120 ismounted;

FIG. 5 is a schematic plan view of a semiconductor wafer 200 including aplurality of interposer regions 201;

FIG. 6 is a partial sectional view showing a step of processing thesemiconductor wafer 200 (a step of forming a conductive material 202);

FIG. 7 is a partial sectional view showing a step of processing thesemiconductor wafer 200 (a step of forming a re-wiring layer 113 andforming the second internal electrodes 142 and the third internalelectrodes 143);

FIG. 8 is a partial sectional view showing a step of processing thesemiconductor wafer 200 (a step of polishing the semiconductor wafer200);

FIG. 9 is a partial sectional view showing a step of processing thesemiconductor wafer 200 (a step of forming a wiring layer 112 and firstinternal electrodes 141);

FIG. 10 is a partial sectional view showing a step of processing thesemiconductor wafer 210 (a step of forming a conductive material 212 andinternal terminals 183);

FIG. 11 is a partial sectional view showing a step of processing thesemiconductor wafer 210 (a step of polishing the semiconductor wafer210);

FIG. 12 is a partial sectional view showing a step of processing thesemiconductor wafer 210 (a step of forming internal terminals 183);

FIG. 13 is a partial sectional view showing laid core chips 131 to 134one on another on the semiconductor wafer 200;

FIG. 14 is a partial sectional view showing the core chips 131 to 134molded at a time with an encapsulating resin layer;

FIG. 15 is a plan view of the semiconductor wafer 200 molded with theencapsulating resin layer 191;

FIG. 16 is a sectional view of a semiconductor memory device 300according to a second embodiment of the present invention;

FIG. 17 is a sectional view of a semiconductor memory device 400according to a third embodiment of the present invention; and

FIG. 18 is a schematic sectional view showing the structure of aconventional semiconductor memory device.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will be explained belowwith reference to the accompanying drawings.

FIG. 1 is a sectional view of a semiconductor memory device 100according to a first embodiment of the present invention.

As shown in FIG. 1, the semiconductor memory device 100 according to thepresent invention has an interposer chip 110 and core chips (four corechips, in this example) 131 to 134. The core chips 131 to 134 aremounted one above another, on a core-mounting surface 110 a (firstsurface) of the interposer chip 110. The core chips 131 to 134 mountedon the core-mounting surface 110 a are molded with an encapsulatingresin layer 191.

On the core-mounting surface 110 a of the interposer chip 110 there areformed first internal electrodes 141. On a core-mounting surface 110 b(second surface) of the interposer chip 110, there are formed secondinternal electrodes 142 and third internal electrodes 143. As shown inFIG. 2, which is a plan view of the interposer chip 110 as viewed fromthe mounting surface 110 b, the second internal electrodes 142 arearranged on a central part of the interposer chip 110. The thirdinternal electrodes 143 are arranged on a circumferential part of theinterposer chip 110, surrounding the second internal electrode 142. Apitch P2 at which the second internal electrodes 142 are arranged isnarrower than a pitch P1 at which the third internal electrodes 143 arearranged. In the present embodiment, the pitch P2 is nearly equal to thepitch P1 at which the first internal electrodes 141 are arranged.

The interposer chip 110 includes a semiconductor substrate 111 made ofsilicon (Si) and re-wiring layers 112 and 113 formed on the surfaces ofthe semiconductor substrate 111, respectively. First through electrodes151 and second through electrodes 152 are provided in the semiconductorsubstrate 111. The first through electrodes 151 connect the firstinternal electrodes 141 to the second internal electrodes 142. Thesecond through electrodes 152 connect the first internal electrodes 141to the third internal electrodes 143. In the present embodiment, there-wiring layer 112 connects the second through electrodes 152 to thefirst internal electrodes 141 that are not aligned with the secondthrough electrodes 152 as viewed in a vertical direction. The re-wiringlayer 113 connects the second through electrodes 152 to the thirdinternal electrodes 143. Preferably, the first through electrode 151 andthe second through electrodes 152 are made of electrical conductor. Ifthey are made of metals, for example copper (Cu), their wiringresistance can be sufficiently low.

The first internal electrodes 141 are connected to internal terminals183 of the core chip 131 that is a bare chip. Therefore, the pitch P1 ofthe first internal electrodes 141 is very narrow, for example about 50μm. Similarly, the pitch P2 of the second internal electrodes 142 isnarrow, about 50 μm, because the second internal electrodes 142 areconnected to the internal terminals of an interface chip, that is a barechip (described later).

In the present embodiment, the pitch of the first through electrodes 151is almost equal to the pitch P1 of the first internal electrodes 141 andthe pitch P2 of the second internal electrodes 142. The first throughelectrodes 151, the first internal electrodes 141 and the secondinternal electrodes 142 are therefore in effect aligned as viewed in thevertical direction. Hence, the wires of the re-wiring layer 112 do notneed to be so arranged to connect the first through electrodes 151 tothe first internal electrodes 141, and wires of the re-wiring layer 113do not need to be so arranged to connect the first through electrodes151 to the second internal electrodes 142.

As described above, the first through electrodes 151, the first internalelectrodes 141 and the second internal electrodes 142 are in effectaligned as viewed in the vertical direction. Therefore, if the pitch P1of the first internal electrodes 141 and the pitch P2 of the secondinternal electrodes 142 are both 50 μm, the pitch at which the firstthrough electrodes 151 are arranged will also be about 50 μm. The firstthrough electrodes 151 can be arrange at such a small pitch, because themain component of the interposer chip 110 is the semiconductor substrate111. If an ordinary substrate made of resin or ceramic is used, thethrough electrodes 51 should not be arranged at such a small pitch inpractice. In view of this, the use of the semiconductor substrate 111 asa main component of the interposer chip 110 is an important feature ofthe present invention. In this respect, this embodiment greatly differsfrom the ordinary modules whose substrate is made of resin, ceramic orthe like.

In an example, in the ordinary substrates made of resin, ceramic or thelike, it is difficult to arrange the through electrodes at a pitch of0.2 mm or less. In the case of a 4×4 mm interface chip 120, the firstthrough electrodes 151 cannot be provided in numbers excess of 400. Ifthe semiconductor substrate 111 is used as in the present invention, thepitch of the through electrodes can be 0.05 mm or less. Hence, throughelectrodes can be formed in a density of 400 pieces/mm² or more.

An ordinary substrate made of resin, ceramic or the like can of coursebe used if re-wiring is performed to increase the pitch of the firstthrough electrodes 151. However, the internal signals transferredbetween the core chips 131 to 134, on the one hand, and the interfacechip 120, on the other, have very small amplitudes. Furthermore, theinternal signals have but a very small driving ability. In view of thesefacts, it is important to arrange the through electrodes at such a verynarrow pitch as in the present invention, not to transfer signalsbetween the core chips 131 to 134 and the interface chip 120 byutilizing a wire of the re-wiring technique.

FIG. 3 is an enlarged sectional view of a section X of shown in FIG. 1.

As shown in FIG. 3, each through electrode 152 (the same applies to thethrough electrode 151) provided in the semiconductor substrate 111 isconnected at one end to the re-wire is composed of a sputtered titaniumlayer 161 and a sputtered copper layer 162 for example, one laid on theother. Another metals which are suitable for wiring, can be useful. There-wire is covered with an insulating layer 170. The sputtered titaniumlayer 161 enhances the bonding between the semiconductor substrate 111and the sputtered copper layer 162. It is desired that the semiconductorsubstrate 111 forming the interposer chip 110 be made thin by means ofpolishing, grinding or the like, although the method of making thesubstrate 111 thin is not limited. More specifically, it suffices toreduce the thickness of the substrate 111 to, for example, about 100 μm.The semiconductor memory device 100 can then be made thin as a whole,while preserving its sufficient mechanical strength.

The core chips 131 to 134 are chips, each having a number of DRAM memorycells. Each core chip has, in addition to the memory cells, a pre-chargecircuit, circuits such as sense amplifiers and address decoders, andcircuits to be used in the wafer test performed on the core chip. Unlikethe ordinary DRAM, the core chip does not have some of the peripheralcircuits, such as input and output circuits that are connected toexternal circuits. Hence, the core chips 131 to 134 cannot be used as anindependent memory. Since the core chips 131 to 134 are not connecteddirectly to external circuits, they have no units, such as buffers,which can output signals to external circuits. They have only input andoutput means that are only sufficient enough to receive and supplysignals within the semiconductor memory device 100.

The core chips 131 to 134 have the third through electrodes 153 and theinternal terminals 183, respectively. Two internal terminals 183 areconnected to the ends of each third through electrodes 153,respectively. The core chips 131 to 134 are connected to the secondinternal electrodes 142 by the first through electors 151 and the thirdthrough electrodes 153. In the present embodiment, the pitch of thefirst through electrodes 151 is equal to the pitch of the third throughelectrodes 153. The first through electrodes 151, the third throughelectrodes 153, the first internal electrodes 141, and the secondinternal electrodes 142 are therefore aligned in effect as viewed in thevertical direction.

It is desired that the core chips 131 to 134 are made thin by means ofpolishing or the like, although the method thereof is not limited. Morespecifically, it suffices to reduce the thickness of the core chips to,for example, about 50 μm.

The semiconductor memory device 100 thus configured is a so-calledunfinished product, and it cannot operate by itself. As shown in FIG. 4,the interface chip 120 is mounted on the mounting surface 110 b of theinterposer chip 110 and connected to the second internal electrodes 142,and the external terminals 150 are formed on the third internalelectrodes 143. The interface chip 120 is molded with an encapsulatingresin layer 192 by means of potting-molding and is thereby protectedphysically. The semiconductor memory device 100 in this state is mountedon a printed board (not shown) or a module board (not shown). Thecombination of the device 100 and the printed or module board isregarded as one large memory unit by external circuits.

The interface chip 120 has peripheral circuits to the core chips 131 to134. These peripheral circuits include address buffers, refreshcounters, and input and output circuits for external circuits. Theinterface chip 120 changes the width of the internal signals it hasreceived via the internal electrodes 141, and changes the width of theexternal signals it has received via the external terminals 150.

When the interface chip 120 is mounted on the mounting surface 110 b ofthe interposer chip 110, it receives the signals (addresses, commands,write data or the like) temporarily supplied through the externalterminals 150. The interface chip 120 expands the width of thesesignals, and the expanded signals are supplied to the core chips 131 to134. The signals (read data or the like) output from the core chips 131to 134 are supplied to the interface chip 120. The interface chip 120compresses the width of these signals. The signals thus compressed areoutput through the external terminals 150.

The first through electrodes 151 that connect the interface chip 120 tothe core chips 131 to 134 are used to transfer internal signals. Thesecond through electrodes 152 that connect the external terminals 150 tothe core chips 131 to 134 are used to supply power. Power can besupplied to the core chips 131 to 134 directly from an external circuitbecause the core chips 131 to 134 have, as described above, no units(e.g., buffers) that must output signals to external circuits, althoughbetween the core units 131 to 134 and any external circuit, signals mustbe transferred through the interface chip 120. Note that the externalterminals 150 are connected to the interface chip 120 by the re-wiringlayer 113 to supply power and signals to the interface chip 120.

As explained above, the interface chip 120 is mounted on thesemiconductor memory device 100 according to this embodiment after thecore chips 131 to 134 are molded. The device 100 can be therefore madeinto products of various specifications. A large number of thesemiconductor memory devices 100 of FIG. 1, each incorporating the corechips 131 to 134, may be stocked, and interface chips 120 of desiredtypes may be mounted on the devices 100 according to the customers'requests. Therefore, the core chips 131 to 134 in the form of bare chipsdo not need to be stocked in large quantities. This makes it possible toflexibly manufacture the product on the customers' demand, whilepreventing the product from being degraded in reliability.

A method of manufacturing the semiconductor memory device 100 accordingto this embodiment will be explained.

First, a semiconductor wafer 200 is prepared as is shown in FIG. 5. Thesemiconductor wafer 200 includes a plurality of interposer regions 201.Each of the interposer regions 201 will be one interposer chip 110. Asshown in FIG. 6, a plurality of trenches are formed in one surface 200 bof each interposer region 201. A conductive material 202 is then appliedand fills the trenches. The conductive material 202 is ultimatelyprocessed into the first through electrodes 151 and the second throughelectrodes 152.

Next, shown in FIG. 7, the re-wiring layer 113 is formed on the surface200 b of the semiconductor wafer 200. Furthermore, the second internalelectrodes 142 and the third internal electrodes 143 are formed on there-wiring layer 113. The process on the surface 200 b of the wafer 200is thus completed.

Subsequently, a support substrate 203 made of, for example, glass isbonded to the surface 200 b of the semiconductor wafer 200 via adhesionas is shown in FIG. 8. The semiconductor wafer 200 in this state isground and polished at the other surface 200 a, until the conductivematerial 202 filled in the trenches is exposed. In other words, thesurface 200 a is made thin to the plane indicated by a line A-A. Theconductive material 202 filled in the trenches is thereby processed intothe first through electrodes 151 and the second through electrodes 152.As shown in FIG. 9, the re-wiring layer 112 is formed on the surface 200a of the semiconductor wafer 200 polished and hence made thin.Furthermore, the internal electrodes 141 are formed on the re-wiringlayer 112. In FIG. 9, semiconductor wafer 200 is mirror reversed causedby upside down.

The semiconductor wafer 200 having a plurality of the interposer chips110 is thus provided.

As shown in FIG. 10, another semiconductor wafer 210 is prepared, whichhas a plurality of DRAM-core regions 211 formed therein. Each of theDRAM-core regions 211 provided in this wafer 210 is processed into onecore chip 131, 132, 133, or 134. As shown in FIG. 10, trenches areformed, in desired numbers, in one surface 210 a of the semiconductorwafer 210. A conductive material 212 is applied and fills the trenches.The conductive material 212 is ultimately processed into the thirdthrough electrodes 153. The trenches may be filled with the conductivematerial, either before or after DRAM cores are formed by a diffusionprocess. The internal terminals 183 are then formed, covering thetrenches filled with the conductive material 212.

Next, as shown in FIG. 11, a support substrate 213 made of, for example,glass is bonded to the surface 210 a of the semiconductor wafer 210. Thesemiconductor wafer 210 in this state is ground and polished at theother surface 210 b, until the conductive material 212 filled in thetrenches is exposed. In other words, the surface 210 b is polished tothe plane indicated by a line B-B. The conductive material 202 filled inthe trenches is thereby processed into the third through electrodes 153and the second through electrodes 152. As shown in FIG. 12, a pluralityof the core chips 131 to 134 are provided when the internal terminals183 are formed on those ends of the third through electrodes 153 whichhave been exposed, and the semiconductor wafer 210 is cut into theDRAM-core regions 211 by using a dicer.

The manufacture of the core chips 131 to 134 is thus completed.

After the semiconductor wafer 200 having a plurality of the interposerchips 110 and the core chips 131 to 134 have been thus provided, theinternal terminals 183 of the core chip 131 are aligned with theinternal electrodes 141 provided on the semiconductor wafer 200. Thecore chip 131 is then hot-pressed onto the semiconductor wafer 200.Furthermore, the core chips 132 to 134 are laid one on another, andhot-pressed onto the core chip 131, such that the internal terminals 183of each core chip contact the corresponding internal terminals 183 ofthe adjacent core chip. Such a process of laying core chips on the firstcore chip is performed for each interposer region 201 of thesemiconductor wafer 200.

After the core chips 131 to 134 are laid one on another, the supportsubstrate 203 is removed as shown in FIG. 14. A protective sheet 204 isthen bonded to the surface 220 b of the semiconductor wafer 200. Thesemiconductor wafer 200 is entirely molded with the encapsulating resinlayer 191, whereby the core chips 131 to 134 are fixed to thesemiconductor wafer 200 and physically protected. Although not shown,the gaps between the semiconductor wafer 200 and the core chips 131 to134 may preferably be filled almost completely by means of underfilling, before the semiconductor wafer 200 is molded with the resinlayer 191. FIG. 15 is a plan view of the semiconductor wafer 200 moldedwith the encapsulating resin layer 191. Note that the protective sheet204 prevents the second internal electrodes 142 from being contaminatedwhile the semiconductor wafer 200 is being molded with the encapsulatingresin layer 191. The support substrate 203 can be used in place of theprotective sheet 204, if it can readily protect the semiconductor wafer200.

The semiconductor wafer 200 is cut into the interposer regions 201, byusing a dicer. A plurality of the semiconductor memory devices 100 ofFIG. 1 can thereby produced.

Thereafter, the interface chip 120 selected by a customer is mounted,and the external terminals 150 is formed. The semiconductor memorydevice 100 of FIG. 4 is then obtained. In this case, the interface chip120 may not be mounted immediately after the semiconductor memory device100 is fabricated. Instead, several semiconductor memory devices 100 maybe stocked, and the interface chip 120 and the external terminals 150may be mounted and formed at the time the customer selects aspecification for the final product. The devices 100 may be stocked inthe form of the semiconductor wafers 200, that is, in the form of beinguncut (see FIG. 15) or in the form of chips (see FIG. 1) provided bycutting the wafer 200. In either case, the devices 100 are stocked, eachwith the protective sheet 204 bonded to the surface 200 b. Theprotective sheet 204 is peeled off immediately before the interface chip120 is mounted and the external terminals 150 are formed. This canprevent the internal electrodes 142 or the like from being contaminatedor corroded.

In the present embodiment, the core chips 131 to 134 are mounted on thesemiconductor wafer 200 having a plurality of the interposer regions 201and are molded at a time with the encapsulating resin layer 191.Therefore, many semiconductor memory devices 100, which are unfinishedproducts, can be provided by cutting the semiconductor wafer 200.Appropriate interface chips 120 that the customers have select can bemounted on the semiconductor memory devices 100, thus easily providingsemiconductor memory devices, i.e., finished products. Thus,semiconductor memory devices can be flexibly manufactured on demand tomeet the customers' needs.

FIG. 16 is a sectional view showing a semiconductor memory device 300according to a second embodiment of the present invention.

The semiconductor memory device 300 according to this embodiment differsfrom the semiconductor memory device 100 described above, in tworespects. First, the interpose chip 110 has no component equivalent tothe re-wiring layer 112. Second, all re-wiring is provided on there-wiring layer 113. Because of these different features, the firstinternal electrodes 141 and the third internal electrodes 143 arealigned as viewed in the vertical direction, by using the re-wiringlayer 113. Hence, in the present embodiment, the pitch of the firstthrough electrodes 151 and the pitch of the second through electrodes152 are substantially equal to the pitch of the first internalelectrodes 141. Although not shown in FIG. 16, the re-wiring layer 113connects the second internal electrodes 142 to the third internalelectrodes 143, as in the first embodiment.

All re-wiring is provided on the re-wiring layer 113 in the secondembodiment. Therefore, the interposer chip 110 can be more easilyfabricated than in the first embodiment.

FIG. 17 is a sectional view showing a semiconductor memory device 400that is a third embodiment of the present invention.

The semiconductor memory device 400 according to the third embodimentdiffers in one respect from the semiconductor memory device 300according to the second embodiment. That is, the first throughelectrodes 151 and the second internal electrodes 142 are not connectedin the same plane. Rather, the second internal electrodes 142 are guidedby the re-wiring layer 113 and are thereby adjusted in position. In thethird embodiment, the first internal electrodes 141 and the secondinternal electrodes 142 do not need to be aligned as viewed in thevertical direction. Thus, the interface chip 120 connected to the secondinternal electrodes 142 can be a general-purpose ASIC or the like, not aspecial ASIC that has electrodes arranged in specific positions.Furthermore, the re-wiring layer 113 can serve not only to adjust thesecond internal electrodes 142 in position, but also to change the pitchof the electrodes.

In the third embodiment, various types of the interface chips 120 can beutilized. Therefore, the semiconductor memory device can be manufacturedat low cost.

While preferred embodiments of the present invention have been describedhereinbefore, the present invention is not limited to the aforementionedembodiments and various modifications can be made without departing fromthe spirit of the present invention. It goes without saying that suchmodifications are included in the scope of the present invention.

For example, while the number of core chips are four in the aboveembodiments, the number is not limited thereto.

In the present invention, the interface chip can be mounted on thesecond surface of the interposer chip whenever desired. Hence, corechips in the form of bare chips do not need to be stocked in greatquantities. Therefore, the products can be flexibly manufactured ondemand to meet the customers' needs, while being prevented from beingdegraded in reliability. Also, since unnecessarily large quantity ofstock can be avoided, the production cost of the semiconductor memorydevices can be reduced.

1-14. (canceled)
 15. A semiconductor device comprising: a first chip; aplurality of first internal electrodes disposed on a first surface ofthe first chip; a plurality of second internal electrodes disposed on asecond surface opposite to the first surface of the first chip, thesecond internal electrodes being arranged in a first pitch; a pluralityof third internal electrodes disposed on the second surface of the firstchip, the third internal electrodes being arranged in a second pitchwhich is larger than the first pitch; a plurality of first throughelectrodes disposed to penetrate the first chip, each of the firstthrough electrodes connecting electrically between one of the firstinternal electrodes and an associated one of the second internalelectrodes; a plurality of second through electrodes disposed topenetrate the first chip, each of the second through electrodesconnecting electrically between one of the first internal electrodes andan associated one of the third internal electrodes; a second chip thatis mounted over the first surface of the first chip and has a pluralityof internal terminals connected respectively to the first internalelectrodes of the first chip; and a third chip that is mounted over thesecond surface of the first chip and has a plurality of internalterminals connected respectively to the second internal electrodes ofthe first chip, wherein the internal terminals of the second chipinclude a set of first terminals and a set of second terminals, each ofthe first terminals being connected to associated one of the secondinternal electrodes by the first through electrodes, and each of thesecond terminals being connected to associated one of the third internalelectrodes by the second through electrodes.
 16. The device as claimedin claim 15, wherein the second chip is a core chip which includes amemory cell to store data.
 17. The device as claimed in claim 16,wherein the third chip includes peripheral circuits to control thesecond chip for storing data.
 18. The device as claimed in claim 15,further comprising a plurality of external terminals, each of theexternal terminals being disposed on the second surface of the firstchip, and each of the external terminals being connected to associatedone of the third internal terminals.
 19. The device as claimed in claim15, further comprising: at least one of fourth internal electrodesdisposed on the second surface of the first chip; and a wiring layerwhich connects one of the fourth internal electrodes and associated oneof the second internal electrodes.
 20. The device as claimed in claim19, wherein the wiring layer is a re-wiring layer, a top surface of there-wiring layer being covered by an insulation layer.
 21. Asemiconductor device comprising: a first chip of semiconductor that hasa plurality of first internal electrodes formed on a first surface, aplurality of second internal electrodes formed on a second surfaceopposite to the first surface of the first chip; and a plurality ofsecond chips of semiconductor that are mounted directly upon each other,and further being mounted on the first surface of the first chip and areconnected to the first internal electrodes, wherein the first chipincludes a plurality of first through electrodes penetrating the firstchip, each of the first through electrodes connecting one of the firstinternal electrodes to associated one of the second internal electrodes,and a pitch of the first through electrodes is substantially equal atleast to the pitch of the first internal electrodes or to the pitch ofthe second internal electrodes.
 22. The device as claimed in claim 21,further comprising: a plurality of third internal electrodes formed onthe second surface of the first chip and arranged in a pitch, which islarger than a pitch of the second internal electrodes; and a pluralityof second through electrodes penetrating the first chip, wherein each ofthe second through electrodes connects one of the third internalelectrodes to associated one of the first internal electrodes.
 23. Thedevice as claimed in claim 22, further comprising a plurality of firstre-wiring layers disposed on the first surface of the first chip, eachof the first re-wiring layers connecting one of the first internalelectrodes and associated one of the second through electrodes.
 24. Thedevice as claimed in claim 21, further comprising a plurality of secondre-wiring layers disposed on the second surface of the first chip, eachof the second re-wiring layers connecting one of the second internalelectrodes and associated one of the first through electrodes.
 25. Thedevice as claimed in claim 24, wherein a part of the second internalelectrodes being connected to the second re-wiring layers are notaligned with positions of the first through electrodes in plan view fromthe second surface of the first chip.
 26. The device as claimed in claim22, further comprising a plurality of third re-wiring layers disposed onthe second surface of the first chip, each of the third re-wiring layersconnecting one of the third internal electrodes and associated one ofthe second through electrodes.
 27. The device as claimed in claim 22,wherein the second internal electrodes are arranged in a central part onthe second surface of the first chip, and the third internal electrodesare arranged in a circumferential part on the second surface of thefirst chip, the second internal electrodes being surrounded by the thirdinternal electrode in plan view from the second surface.
 28. The deviceas claimed in claim 21, wherein the pitch of the first throughelectrodes is less than 0.2 mm.
 29. The semiconductor memory device asclaimed in claim 21, further comprising an encapsulating resin layerthat is provided over the first surface of the first chip and molds thesecond chips.
 30. The device as claimed in claim 21, wherein each of thesecond chips is a core chip which includes a memory cell to store data.31. The device as claimed in claim 22, wherein a part of the secondthrough electrodes are used for a power supply to the second chips. 32.The device as claimed in claim 30, further comprising a third chip thatis mounted on the second surface of the first chip and is connected tothe second internal electrodes, wherein the third chip includesperipheral circuits to control the second chip for storing data.
 33. Thedevice as claimed in claim 32, further comprising an encapsulating resinlayer that is provided over the second surface of the first chip andmolds the third chip.
 34. A semiconductor device comprising: a firstsemiconductor chip that has a plurality of first internal electrodesformed on a first surface, a plurality of second internal electrodesformed on a second surface opposite to the first surface, a plurality ofthird internal electrodes formed on the second surface and arranged in apitch, which is larger than a pitch of the second internal electrodes;and a plurality of second semiconductor chips that are mounted directlyupon each other, and further being mounted on the first surface of thefirst semiconductor chip and are connected to the first internalelectrodes, wherein the first semiconductor chip includes a plurality offirst through electrodes penetrating the first chip and connecting apart of the first internal electrodes to a part of the second internalelectrodes, and a plurality of second through electrodes penetrating thefirst semiconductor chip and connecting a remaining part of the firstinternal electrodes to a part of the third internal electrodes, and apitch of the first through electrodes is substantially equal at least tothe pitch of the first internal electrodes or to the pitch of the secondinternal electrodes.